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Microbes Hitchhike Across Atlantic

Dust storms in Africa blow bacteria to Western Hemisphere, says study

WEDNESDAY, July 4, 2001 (HealthDayNews) -- When the wind kicks up in the African desert, giant dust plumes begin their journey across the Atlantic, carrying some hearty -- and potentially harmful -- microbes on a free trans-oceanic ride, a new study says.

Ginger Garrison, a marine ecologist with the US geological survey, and the study's lead author, decided to track dust clouds after getting sick while in Mali, a poor west African country. "I've never breathed air and had my lungs burn before. I thought, there's more than just dust happening here."

The National Institutes of Health estimates 40 million to 50 million Americans suffer each year from allergic diseases, with airborne dust causing the most problems worldwide.

Last July Garrison began collecting daily samples of airborne pollutants and dust on St. John in the American Virgin Islands, sending them to the U.S. Geological Survey in Florida for microbe analysis.

"In the very first sample of dust from the Virgin Islands, we found the pathogenic form of the same species of fungus that is known to cause Sea Fan Disease," which affects Caribbean coral, Garrison says.

Then, using NASA's Total Ozone Mapping Spectrometer (TOMS) satellite instrument, the team pinpointed the path of dust clouds from Northern Africa and time their arrival in St. John. They discovered the air samples containing high levels of microbes corresponded to the days the African dust swept into the Caribbean.

Researchers say more than 50 percent of the microbe-laden African dust lands in Florida each year, but not all the fungi and bacteria are disease producing.

Previous research has shown that about 13 million tons of African dust falls in the Northeastern Amazon Basin from February to April, with a wind shift carrying the dust to North and Central America and the Caribbean from June to October.

The dust takes about five to seven days to cross the ocean, and although the sun's ultraviolet (UV) rays kill many microbes, the researchers say "microbes in the cracks and crevasses of dust particles may be shielded from UV…[and] the upper altitudes of the dust clouds deflect the harmful UV rays, shielding microbes at lower altitudes as they are transported across the Atlantic Ocean."

The moderate temperatures and high humidity over the open water in lower latitudes may also enhance the survival of the microbes, the study says.

Desert dust has been identified, say the researchers, as the cause of Aspergillosis, a mold-like infection of the lungs that affects animals, especially birds. Also coccidioidomycosis, which causes lung illnesses in humans, ranging from flu-like symptoms to pneumonia, has been found in the arid Southwestern U.S.

The bacteria and fungi often come from contaminated soil and water in the developing countries, and a global effort is needed to stem the problem, says Garrison.

More preventive measures are needed such as "improving the sewage system, potable water and covering the soil. Instead of pointing fingers, there should be help between nations in transport technologies."

Then, "once we get a better idea of the basic scientific processes going on to cause disease to run rampant on coral reefs and which effect human health, we'll be in a better position to make recommendations to the federal government on the next best step," says Garrison.

"People need to be very aware of how small our planet is and what every person does affects somebody on the other side of the world," says Garrison.

But, we should be equally aware of how the things we do disturb the people next to us, says Dr. Martha V. White, an allergist and director of research at the Institute for Asthma and spokeswoman for the American Academy of Allergy, Asthma and Immunology.

White says she has not seen any data that shows the problems of airborne pollutants are getting worse and suggests controlling those things we can. "We smoke, we wear scented cologne, perfumes, aftershave. A certain amount of smells are OK, but no matter how lovely the scent, if you wear too much of it…those are things to think about."

The study's findings are outlined in the recent issue of Aerobiologia.

What To Do

The Environmental Protection Agency has a state-by-state listing of air quality.

You may also want to read up on the Lung Association's list of lung diseases A to Z.

SOURCES: Interviews with Ginger Garrison, marine ecologist, with the US Geological Survey and study co-author; Martha V. White, allergist, director of research at the Institute for Asthma and spokeswoman for the American Academy of Allergy, Asthma and Immunology; June 14, 2001 Aerobiologia
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